It probably is that, makes sense. Not sure what devices would be doing it… (Xfinity router?). I even moved to a new house with different devices, router etc and it still did that.
My Windows 10 machine comes up from sleep when nobody is anywhere near it. Seems weird to me. Also sometimes I wake it, sign in and the folder Music>Pictures (the regular Pictures folder… for some reason that’s where it is) is open in explorer. Couldn’t figure out whether it’s malware or Microsoft.
You’re right, it could be a setting in Windows or perhaps the BIOS. I know there is often a ‘wake on LAN’ BIOS setting…